1. Field of the Invention
This invention relates to cleansing compositions and in particular it relates to such compositions, containing an antibacterial compound and a surfactant which are suitable for skin cleansing. The compositions of the invention are useful in surgical practice as a pre-operative scrub; and may be used routinely by hospital ward staff.
2. Description of the Prior Art
The essential constituents in this type of cleaning composition are an antiseptic agent and a surfactant. An antiseptic agent which, in recent years, has come to the fore as particularly effective is chlorhexidine, i.e., 1,6-di-(4-chlorophenyldiguanido)hexane, and salts thereof. However, many common surfactants are incompatible with many antiseptic agents, particularly chlorhexidine. Thus, anionic surfactants are known to destroy the antibacterial activity of chlorhexidine solutions by complexing with the cationic chlorhexidine, and cationic surfactants are not preferred because of their irritancy, and because, in combination with a soluble chlorhexidine salt, double decomposition can occur with the formation of insoluble chlorhexidine salts and consequent loss of antibacterial activity. Amphoteric surfactants, which contain either anionic or cationic centers, depending upon pH, suffer from the above-described disadvantages of anionic and cationic surfactants, and are therefore equally unsuitable for the present purpose.
U.S. Pat. No. 3,960,745, a continuation of U.S. Pat. No. 3,855,140, discloses such cleansing compositions containing a soluble salt of chlorhexidine, a polyoxyethylene-polyoxypropylene block co-polymer and an inert diluent or carrier. Particularly preferred block copolymers are those sold under the trademark Pluronic, particularly the Pluronic P-84, P-85 and F-87 surfactants. However, this patent indicates in column 2 that for user acceptability, it is necessary to include an additional foaming agent in order to get adequate foaming. The patent says,
"Most foaming agents deactivate chlorhexidine to a large extent, but with amine oxide foaming agents the deactivation is kept to a minimum. Nevertheless, some deactivation is unavoidable, so it is preferable to use a surfactant having maximum foaming properties so that the quantity of deactivating foaming agent is kept to a minimum."
The patent indicates that Pluronic polyols P-84, P-85 and F-87 have the greatest foaming ability and with these the addition of 3.75 percent of an amine oxide foaming agent gives a composition having acceptable foaming properties but that with other Pluronic polyols, it is necessary to increase the quantity of additional foaming agent and to increase also the quantity of chlorhexidine in order to overcome the deactivating effect of additional foaming agent.
All the preferred Pluronic polyols of the patent have a hydrophobe molecular weight of 2250 and contain between 40 and 70 percent polyoxyethylene groups by weight. It is known from the published literature of the BASF Wyandotte Corporation that increasing or decreasing the hydrophobe molecular weight decreases the foaming properties of the Pluronic polyols alone. Accordingly, it would be desirable to have a cleansing composition employing an antiseptic agent and a nonionic surfactant which requires less and preferably no additional foaming agent even when said surfactant has a considerably lower molecular weight than 2250 for the hydrophobic group.
U.S. Pat. No. Re. 29,909 discloses aqueous detergent solutions of block copolymers of PO-EO such as the Pluronic polyols which may contain antiseptic agents. The Pluronic polyols employed should have an ethylene oxide content of at least 75 percent, the antiseptic agents disclosed do not include chlorhexidine.
U.S. Pat. No. 2,828,345 discloses products prepared by first condensing butylene oxide with a butylene glycol to form a polyoxybutylene glycol having a molecular weight greater than 1000 and thereafter condensing ethylene oxide with the polyoxybutylene glycol until the so-prepared product has an oxyethylene content of from 20 to 90 percent by weight. Suitable butylene oxides listed include, 1,2-butylene oxide.
U.S. Pat. No. 4,200,733 discloses block copolymers which contain from 5 to 25 percent by weight of bonded iodine and which are based on iodine-free compounds which are block polymers of (A) a polymer or copolymer block of from 4 to 100, 1,4-butylene oxide units, and from 0 to 25 ethylene oxide units, and (B) a copolymer block of from 0 to 50 1,4-butylene oxide units and from 1 to 100 ethylene oxide units, the proportion of 1,4-butylene oxide being greater than 50 mole percent in (A) and less than 50 mole percent in (B).
For a skin cleansing composition containing an antibacterial compound, it is necessary to have a composition that exhibits high foaming, as previously pointed out, together with good solubility in water, non-irritancy to the skin, and adequate detergency.